To
resolve the issue that the "Symptoms" section describes, edit the registry, and
then set the permissions in Exchange 2003 or in Exchange 2000. To do this, follow these steps.

Important This section, method, or task contains steps that tell you how to modify the registry. However, serious problems might occur if you modify the registry incorrectly. Therefore, make sure that you follow these steps carefully. For added protection, back up the registry before you modify it. Then, you can restore the registry if a problem occurs. For more information about how to back up and restore the registry, click the following article number to view the article in the Microsoft Knowledge Base:

Warning If you have any programs that use the IAddressee::GetFreeBusy function from Collaboration Data Objects for Exchange 2000 on the
affected server, the IAddressee::GetFreeBusy function stops working if you add the following registry key. In most scenarios in which this registry key
is added, the function returns an error code of 0x8000FFFF.

ADSI Edit is included with the Windows Support Tools. You
can install the Windows Support Tools from the Support\Tools folder of the
Windows 2000 Server CD-ROM or the Windows Server 2003 CD-ROM.
For more information
about how to install the Windows Support Tools for Windows
2000, click the following article number to view the article in the Microsoft Knowledge Base: